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通过观察取向硅钢的低倍组织,分析水冷和空冷及铌的加入对铸态组织的影响,并结合金相显微镜、扫描电镜对铸态组织进行了观察及表征。对比分析了含铌取向硅钢与不含铌取向硅钢的铸态组织的差异。试验结果表明:经空冷处理的含铌铸坯其铸态组织有非常明显粗大的柱状晶,所占体积分数约64%,表层的细晶区很薄,中心是更细小的等轴晶。而采用水冷处理的含铌铸坯组织以中心等轴晶为主,所占体积分数约78%,柱状晶较小不明显。经相同水冷条件,不含铌的铸坯得到的铸态组织中其晶粒尺寸比含铌的偏大,其柱状晶比含铌铸坯的明显,中心等轴晶所占体积分数较少(约41%),说明铌的加入能使铸坯晶粒更均匀细小。
By observing the microstructures of oriented silicon steel, the effects of water cooling and air cooling and niobium addition on the as-cast microstructure were analyzed. The as-cast microstructure was observed and characterized by metallographic microscope and scanning electron microscope. The differences of as-cast microstructures between niobium-containing oriented silicon steel and non-niobium oriented silicon steel were compared and analyzed. The experimental results show that the as-cast Nb-containing slab has an obvious and coarse columnar crystal, accounting for about 64% of the volume fraction. The fine-grained zone in the surface layer is very thin and the center is a finer equiaxed grain. However, the structure of niobium slab treated by water-cooling is dominated by central equiaxed grains, accounting for about 78% of the volume fraction, and the columnar grains are not obvious. Under the same water cooling condition, the grain size of the as-cast structure obtained from the slab without niobium is larger than that of the niobium-containing slab, and the columnar grains have obviously smaller volume fraction than the center-containing equiaxed grains About 41%), indicating that the addition of niobium can make the slab grain more uniform and small.